1. Quotation: The most general term, simply meaning a passage reproduced verbatim from another source.
2. Epigraph: A short quotation at the beginning of a work that sets a theme or provides context.
3. Intertextuality: A broader concept that refers to the way texts relate to and influence each other, including the use of quotations.
4. Allusion: A brief and indirect reference to a person, place, thing, or event from history, literature, or mythology. While not a direct quotation, it can be considered a kind of "borrowed" language.
5. Plagiarism: Using someone else's work without attribution, which is unethical and often illegal. This is a negative term and should not be used to describe a legitimate use of another's work.
The best term to use depends on the specific situation.